At 22, it’s not socially acceptable for me to spend hours on the swing set, but that doesn’t mean I have to ignore my inner child completely. After trying a very “grown-up” Pilates-and-strength-training class in July, I was itching for something more playful to shake up my workout routine. So I opted for the unconventional Urban Rebounding class: a low-impact cardio workout on a mini trampoline.

If you’re afraid of bouncing too high (I, too, was under a self-enforced trampoline ban after a bounce-gone-bad in high school), don’t worry — Urban Rebounding trampolines, which are officially called “rebounders,” are individual-sized and reassuringly low to the ground.

But that doesn’t mean rebounding is slow-paced. The class uses familiar aerobics moves like hamstring curls and squats, but adds simultaneous, fast jumping. Imagine your casual backyard bounce — at triple the speed. The Urban Rebounding class at New York City’s Crunch gym, where I took my class, involved 45 minutes of combined abs, cardio and light weight-lifting — and I felt the burn all over. “This is one of our most popular classes and people enjoy it because anyone can do it, it’s fun and you’re getting a full-body workout in one class,” says instructor Carissa Toro.

Martial arts expert and personal trainer J.B. Berns developed both the class and the rebounder in 1996. At the time, he was nursing a knee injury and needed a workout that was easy on his joints. Since the mid-’90s, rebounding classes have spread to more than 5,000 gyms worldwide.

The bouncing workout has become popular among cardio junkies, runners and even elderly gym goers because working out on a trampoline reduces joint and knee impact. My class at Crunch was packed with twentysomething gym bunnies, but that’s not always the case. “A class I taught earlier was mainly all seniors,” my instructor Carissa Toro said.

The workout is tough — rebounding pushes your muscles to fatigue — but has a lower risk of injury. Bouncing also increases both your blood flow and lymphatic-fluid circulation, which is good for active muscles too. As for what it does for the shape of your body? “Sexy, sexy, sexy,” says Toro.

A warning: consistent trampoline training may lead to sleek and sexy limbs, but during the workout, you’ll look anything but sensuous. In fact, be prepared to look very silly and very sweaty.

More and more gyms are incorporating trampolines into their standard classes, including yoga and Pilates. If you can’t find a class at your gym, you can purchase Berns’ entire system with rebounder and workout DVDs for home use for about $99.95.